Heterogeneous 2D nucleation of the stable polymorphic form on the metastable form

Abstract For the determination of the metastable zone width, that is the supersaturation needed to observe nucleated crystals in a given time, it is essential to have control of which polymorph is formed. For heterogeneous nucleation, the metastable zone width can be significantly lowered. This paper discusses a special case of heterogeneous nucleation for which the stable phase of a steroid nucleates on specific faces of the metastable one.